Each was a young girl depicted in salacious photos that spread digitally. Each committed suicide after suffering from the humiliation of that distribution - the shame of being cyberbullied, their parents say.

It's a list that only figures to grow, experts and victims' parents say, thanks to the expansion of the smartphone texting culture and the increasing callousness that people display when they talk electronically rather than in person.

Polls suggest the percentage of teenagers who experience cyberbullying is rising - from the 6 percent reported by the University of New Hampshire in 2000, to 72 percent in a 2008 poll by UCLA psychologists, to 85 percent in a recent survey by Wired Safety, a group that fights online crime.

"Frankly, texting is something that gets overlooked when we talk about cyberbullying, but it is exploding as a problem," said Dr. Tim King, a visiting professor of sociology at UC Berkeley, who studies technological harassment.

"Bullying has been around since the dawn of time," he said, "but now with new media it's bullying combined with the weapon of mass publication to a mass audience. Smartphones make that mass publication instantaneous."

Audrie Pott's parents say she was sexually assaulted in September by three Saratoga High School classmates while intoxicated and unconscious, and then hanged herself a week later after learning that a picture of her nearly naked, abused body had been shared on cell phones.

The 15-year-old didn't know if the image was seen by 10 students or thousands, but by the time of her suicide she believed "everyone" knew what had happened to her, said Lawrence and Sheila Pott.

Instant audience

But the number of actual eyeballs isn't critical, said Holly Pedersen, director of the bullying prevention program at Parents Place in Palo Alto, a family resource center.

That's because youths are so intricately enmeshed with their phones and their digital identities that on a core level they know whatever is sent out can potentially be seen - instantly - by multitudes, Pedersen said.

Unfortunately, because minors are still developing critical-thinking skills and often can't effectively link action to consequence, those who send the pictures don't understand the impact of that digital reach - the potential to hurt someone.

"If they were still stuck with just computers, or even the old slower phones, they might have to think about their actions more before they take them as they walk or drive home," Pedersen said. "Instead, now they can click on it right away, sending something out before they take a breath first.

Audrie's photos were never posted online, students and family members said, but that didn't stop it from being shared around campus.

"My friend approached me and said, 'I saw these pictures of these people,' and I was like, 'No way, really?' " said Mateen Tabrizi, 17, a senior at Saratoga High. "He said, 'Yeah, look at the photos,' and he grabbed the phone out of someone's hand and showed it to me. I thought it was pretty messed up."

Tragic mistake

Donna Witsell's 13-year-old daughter experienced the worst of this phenomenon.

Hope Witsell, a churchgoing, straight-A student in Florida, made the mistake of texting a boy she liked a picture of her breasts. When a rival girl got hold of the photo and texted it around their school, it went viral almost instantly. After enduring taunts electronically and in person, she hanged herself in September 2009.

Since then, Donna Witsell has become an activist against cyberbullying, calling it "an epidemic."

"It's only getting worse, and I hear from kids and parents all over the country," she said in a phone interview from her Florida home. "All this awareness doesn't seem to be making any difference. You see cyberbullying laws in many states and school districts, but is it stopping? No."

Public schools in California aren't required to teach cyberbullying prevention, though the state Board of Education provides resources for districts that choose to, said Tom Herman, a board administrator. Many districts, including the one serving Audrie, conduct student assemblies and parent-staff meetings to address the issue.

The state Education Code allows districts to expel a student who cyberbullies another. But after Audrie was allegedly assaulted by the three boys, the Los Gatos-Saratoga Joint Union High School District did not expel them because the incident happened off campus. The district can expel only for acts "related to school activity or attendance," according to a district statement.

The two boys who played on the school's football team were kicked off of it because "participation in sports is a privilege," and that left more latitude for action, the district said.

The district also said Audrie "never reported or sought counseling for bullying." If she had, officials said, "our staff would have reported it and taken preventative steps to stop it."

That Audrie didn't speak up should be no surprise, experts say. The state Department of Justice's guidelines on cyberbullying say only 5 percent of students tell their parents when they've been cyberbullied.

Audrie's parents are pushing state legislators to stiffen the education code to make it easier for administrators to go after student cyberbullies - whether or not there is a firm connection to school activities.

Documenting acts

It's hard to understand why three boys would take a photo that incriminates them, as is alleged in Audrie's case. But experts say teens who share news and activities through social media subscribe to a documentation mentality reflecting the oft-used phrase "pictures, or it didn't happen."

"Maybe they were drunk and being dumb," said Mateen, the classmate. "They were probably like, 'Oh, I want to show it to my friends.' People like to take pictures because if you approach someone and tell them something crazy, they won't believe it otherwise.

"But taking pictures of your own crime? That's rookie s-."

Teens who spread information using electronics also often feel a "dissociative anonymity," said King, the UC Berkeley professor.

"People become a bit dissociated with what they do on the Internet, or distributing materials by text, because they tend to think it's not a real place," he said. "They become uninhibited. There is a feeling of anonymity, so they feel freer to say whatever they want."

That freedom can translate into nastiness, he said, as teens - and adults - feel it's OK to type out offensive things they wouldn't dare say face to face.

Such dissociation gets blamed as a contributing factor in virtually every cyberbullying suicide, such as that of two Canadian girls, Amanda Todd, 15, and Rehtaeh Parsons, 17.

Amanda killed herself in October after posting a YouTube video, seen by millions, pleading for an end to the harassment that followed the electronic dissemination of a photo of her breasts. Rehtaeh hanged herself on April 4 after one of four boys accused of raping her distributed a photo of her having sex.

In both cases, even after death, cruel taunts continued.

'Rape culture'

Students at Palo Alto High School became better acquainted with the phenomenon of callousness when their high school's newsmagazine, Verde, published a cover package on "rape culture" in early April.

The main story profiled two students who described their experiences with date rape. One of the girls said the blame and gossip she encountered included texts, Facebook messages and Tumblr posts.

The two girls "received an overwhelming lack of support from their friends," said Evelyn Wang, one of the editors-in-chief of Verde. "They were blamed for what happened to them."

Even though they were familiar with "rape culture" among their peers, Wang and the rest of the magazine staff were surprised at the electronic heartlessness the victims faced.

"I think the social-media element made it much more difficult for a victim or survivor to come out and talk about what happened to them or to escape the stigma that surrounds a victim," Wang said.